Recently, an optical unit including a rotary reflector that rotates in one direction around its rotation axis while reflecting light emitted from a light source has been devised (see JPWO 2011129105 (A1)).
This optical unit can form a light distribution pattern partially shielded by controlling the timing of the turning on/off of the light source while scanning the front side of the optical unit with a light source image.
However, in the above-described optical unit, all of the scanning regions that can be scanned by the reflected light reflected in each of a plurality of blades are the same. Therefore, in the scanning regions, an irradiated region and a non-irradiated region divided in a scanning direction can be formed, but an irradiated region and a non-irradiated region divided in a direction intersecting with the scanning direction cannot be formed.